Advances in automotive acoustics have led to a quieter vehicle interior. Not only are these advances aimed at reducing the noise from the engine, but also toward reducing noises reaching the cabin from externally, such as road noise and the like. This means that sound emissions from systems in the interior cabin that run while the vehicle is being driven have become more apparent. Accordingly, there is the need to reduce the sound emission of these systems as well.
In vehicles with pneumatically adjustable seats, in which one or more bladders is inflated and deflated to adjust an adjacent portion of the seating surface, the seat adjustment system is one such system that is intermittently active during vehicle use. In particular, the pressures in the air bladders are controlled through a module with a number of valves. Each of these valves can inflate and deflate the bladders that are connected to this valve. The air pressure is supplied by one or more pumps. The main cause of noise of this system is the pump, but also the air rushing in the tubes and rushing into the bladder can make a significant amount of additional noise. The frequency of the sound emitted by the pump depends on the speed (measured in revolutions-per-minute (“RPM”)) of the pump. In some implementations the control systems of such seats may not have one set pump speed, but may use multiple speeds, depending on the airflow need at a given instance. Known solutions for filtering or otherwise reducing pump noise within such a pneumatic system can cancel out or reduce a primary frequency for which they are tuned but cannot compensate for the use of a pump at varying speeds or the like.